From mboxrd@z Thu Jan  1 00:00:00 1970
From: Guenter Roeck <linux@roeck-us.net>
Subject: Re: [RFC 22/37] watchdog: renesas_wdt: Add restart support
Date: Fri, 26 Jan 2018 09:14:18 -0800
Message-ID: <20180126171418.GA16194@roeck-us.net>
References: <1516903391-30467-1-git-send-email-fabrizio.castro@bp.renesas.com>
 <1516903391-30467-23-git-send-email-fabrizio.castro@bp.renesas.com>
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To: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Wim Van Sebroeck <wim@iguana.be>, Russell King <linux@armlinux.org.uk>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@codeaurora.org>, Simon Horman <horms@verge.net.au>, Magnus Damm <magnus.damm@gmail.com>, Geert Uytterhoeven <geert+renesas@glider.be>, devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, Chris Paterson <Chris.Paterson2@renesas.com>, Biju Das <biju.das@bp.renesas.com>, Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renes>
List-Id: devicetree@vger.kernel.org

On Thu, Jan 25, 2018 at 06:02:56PM +0000, Fabrizio Castro wrote:
> This commit extends the driver to add restart support by implementing
> the restart callback to trigger the watchdog as quickly as possible.
> 
> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
> ---
>  drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index 831ef83..120ddac 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
>  	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
>  }
>  
> +static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
> +			void *data)
> +{
> +	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	pm_runtime_get_sync(wdev->parent);
> +
> +	rwdt_write(priv, 0x00, RWTCSRB);
> +	rwdt_write(priv, 0x00, RWTCSRA);
> +	rwdt_write(priv, 0xffff, RWTCNT);
> +
> +	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> +		cpu_relax();

Can this get stuck forever or should there be a timeout ?

Guenter

> +
> +	rwdt_write(priv, 0x80, RWTCSRA);
> +	return 0;
> +}
> +
>  static const struct watchdog_info rwdt_ident = {
>  	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
>  	.identity = "Renesas WDT Watchdog",
> @@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
>  	.stop = rwdt_stop,
>  	.ping = rwdt_init_timeout,
>  	.get_timeleft = rwdt_get_timeleft,
> +	.restart = rwdt_restart,
>  };
>  
>  static int rwdt_probe(struct platform_device *pdev)
> -- 
> 2.7.4
> 
> --
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